A typical stationary gas turbine arrangement provides a burner with a combustor in which hot gases are produced which flow into a turbine stage in which the hot gases performing expansion work. The turbine stage consists of a rotary shaft on which a multitude of blades are arranged and grouped in axially blade rows. The rotary unit is encapsulated by a stationary casing on which vanes are mounted which are also divided in axial distributed vane rows each extending between the blade rows. For performing maintenance work on a typical stationary gas turbine, it is necessary to lift the uppercasing half of the turbine stage to get access to the rotary unit. In most of the cases, it is unavoidable to remove also the rotary unit from the lower casing half for further disassembling work. It is a matter of fact that maintenance work on conventional stationary gas turbines is time and cost consuming which is a significant disadvantage for the gas turbine operating company.
Basically it is known that for inspection work inside the outer casing of a turbine stage so called manholes are integrated, so that worker person can gain access to the inner core of the stationary components of the first turbine stage. However, it is not possible to get a direct access to the vanes or blades extending inside the turbine stage because the stationary components, which carry the blades divided in several axially blade rows are typically manufactured in one piece having an axial extension of the length of the turbine stage. In FIG. 2, a rough sketch illustrates a longitudinal section view through the first stage gas turbine in the region of the first vane 1 and blade 2. Hot gases 3, which are produced inside a combustor 4 flow through the funnel shaped entrance opening 5 of a first turbine stage 6. Hot gases 3 pass in axial direction through circumferential interspaces between the blades 1, which are arranged circumferentially around the rotor axis 7 of the rotor unit 8. Each vane 1 provides a radial outer platform 9, an airfoil 1′ and a radial inner platform 10. The radial outer platform 9 contains mounting hooks 11, which are inserted into mounting groves 12 of the stationary component 13 of the first turbine stage. The inner platform 10 of vane 1 typically encloses a gap 14 with the inner combustor liner 15 through which a purge flow of cooling medium 16 can be injected into the hot gas flow 3. In the same way a purge flow of cooling medium 16′ is injected through a gap 14′ that is enclosed by parts of the stationary component 13, the upstream edge of the platform 9 of vane 1 and the outer combustor liner 15′. Downstream the outer platform 9 a heat shield 9′ is mounted inside of the stationary component 13 which prevents overheating of the inner faced areas of the stationary component in the same way as in case of the outer platform 9.
EP 2 447 475 A2 discloses an airfoil attachment arrangement in which the airfoil 46 is mounted between an outer and inner platform 48, 50. For mounting and demounting purposes in the outer platform 50, an aperture 90 is processed through which the airfoil can be moved radially. Also at the inner platform 48, (see FIG. 11) there is an opening (see FIGS. 11 to 13) through which the radial inner end of the airfoil 46 penetrates partially. Both ends of the airfoil 46 are fixed by retention assemblies. FIGS. 4 and 5 show a retention assembly 54 for fixing the radial outward end of the airfoil 46. FIG. 12 shows a retention assembly 126 for fixing the radially inner end of the airfoil 46.
U.S. Pat. No. 6,189,211 B1 discloses a method and arrangement for carrying out repair and/or maintenance work in the inner casing of a multi-shell turbo machine. For getting access to the vanes of the first row a man hole 21 is provided within the outer casing of the gas turbine plant. For getting access to the row of vanes, the top part of the combustion chamber casing 12 can be lifted off by a lifting device 33 as disclosed in FIG. 2.
U.S. Pat. No. 3,004,750 A discloses a stator for compressor or turbine arrangement which shows especially turbine arrangement which shows especially in FIGS. 1 to 4 that in a stationary component which is the shroud 2 several through-holes 8 are provided through each of which a vane 6 can be inserted. Each vane 6 provides at its radially outer end a so called foot 10 overlying the outer surface of the outer shroud 2, so that when the vane 6 is inserted into the slot 8, the slot is sealed air tightly especially by welding 12 the foot 10 against the outer surface of the shroud 2. The radially inner end of the vane 6 extends into a slot 26 in the inner shroud 4. Inside the slot 26, there is a spring pin 32, which provides a damping effect on the vane 6.
A similar construction of mounting of vanes 34 within a gas turbine engine is disclosed in U.S. Pat. No. 4,643,636 A, which shows an assembly including a ceramic inner and outer shroud rings in which recesses are provided through which vanes can radially mounted therein. For securing of the vanes a ceramic outer support ring 40 slides over the outer shroud ring
FR 2 671 140 A1 discloses guide vanes for a turbo machine compressor (see FIG. 1). Inside the outer shroud segment 2, through-holes 7 are provided through which vanes 3 can be inserted radially. The radially inner end of the vane is received by a slot of an inner ring segment 4. The vane 3 can be secured by a fixing plate 9, which is pressed inside a recess 10 at a mounting device 8 fixed on the outer shroud 2.